Multiply by Powers of 10
10 x 13.45
134.5
4.5 x 19.8
5 x 20 = 100
0.2 x 0.1
0.02
Create an area model to solve 0.8 x 5.4
4.32
Multiply 35.4 x 2.3
81.42
0.4 x 102
40
8 x 56.7
8 x 60 = 480
or 8 x 57 = 456
0.3 x 0.4
0.12
Create an area model to solve 1.1 x 2.2
2.42
14 x 9.67
135.38
4.65 x 100
4.65
8.2 x 3.09
8 x 3 = 24
0.9 x 0.8
0.72
Create an area model to solve 4.3 x 5.2
22.36
Which of the following is not a power of 10
a) 103
b) 10 x 10 x 1
c) 3.5 x 10
d) 103x 0.001
c
3.5 x 10 = 35
35 cannot be written as a power of 10
17.5 x 103
17,500
.38 x 99
(hint: only round 99 to get a closer estimate)
.38 x 100 = 38
0.9 x 0.1
0.09
Create an area model to solve 12 x 3.4
40.8 or 40.80
Patti went to the bakery. She bought a loaf of bread for 3.49 and 4 muffins that cost 1.25 each. She also bought a bottle of juice that costs 2.75. How much did she spend all together?
All together, the muffins cost $5.00, the bread costs $3.49 and the juice costs $2.75
3.49 + 5.00 = 8.49
8.49 + 2.75= 11.24
She spent $11.24
10,000 x 10.43
104,300
11 x 4.89
11 x 5 = 55
or
10 x 4.89 = 48.9
or10 x 5 = 50
1.2 x 0.4
0.48
Create an area model to solve 6.8 x 12.3
83.64
The digits in the product of 0.48 and a decimal number between 350 and 400 are 182136. Without knowing the other factor, where should the decimal go?
182.136
We can imagine that the other number is somewhere near 400 so we can use an estimate
0.5 x 400 = 200
So our answer needs to be somewhere near 200.